As for a hybrid electric vehicle and an electric vehicle, a high-power brushless motor is used and furthermore a higher power motor will be expected. To control the brushless motor of a hybrid electric vehicle, it is necessary to accurately ascertain the rotation angle of an output shaft of the motor. This is because the rotation position (angle) of a rotor needs to be correctly ascertained in order to control switching of energization of coils of a stator.
Accordingly, the motor preferably includes a resolver to accurately detect the angle. Such resolver used in a drive mechanism of a vehicle is required to provide high accuracy in addition to environment resistance because of the high number of revolutions of the drive mechanism. As with other in-vehicle components, the resolver is also demanded to achieve size reduction and cost reduction.
Patent Literature 1 discloses a sheet coil in which a A-phase detection coil is placed on a surface of an insulating sheet layer and a B-phase detection coil is placed on the other surface of the same. Herein, the A-phase detection coil and the B-phase detection coil are shifted 90° in phase from each other. An excitation coil is also formed as a sheet coil. The excitation coil and the detection coil are spaced to face each other with a predetermined gap therebetween.
Patent Literature 2 discloses a resolver as shown in FIG. 18 in which excitation coils are formed on a front surface (facing a stator-side base plate) and a back surface of a rotor-side base plate, a SIN (sine) coil is formed on a front surface (facing the rotor-side base plate) of the stator-side base plate, and a COS (cosine) coil is formed on a back surface of the same.